Modern data centers and telecommunication systems regularly use alternating current (AC) power sources to operate various electric loads, for example, servers. In applications such as data centers, the high availability and redundancy of the AC power sources is important. However, sometimes AC power sources can malfunction and introduce faulty conditions in systems that they are powering. AC line faults can include short circuit and open circuit conditions. AC line faults can have adverse impacts on system performance, can damage system components, and can have other undesirable consequences such as automatic and abrupt shutdown of the system. In conventional systems, there is a significant period of time that elapses between when the fault occurs and when the fault is detected. In some situations, the delay can be around 10 milliseconds or more. Fast detection of faulty AC line conditions would be desirable, so that the faulty conditions can be promptly addressed.